Blade components have a characteristic form factor; they have a thickness dimension substantially smaller that their height and width. This provides a convenient packaging arrangement for a large system, wherein multiple blades can be inserted in slots in a chassis, each blade providing a standalone capability, and each blade replaceable if problems develop.
Advanced packaging technology may be applied to reduce the dimensions of such a blade assembly. However, dissipating the heat generated in such a miniaturized version is difficult. It is helpful to make the blade as thin as possible. This provides short paths for the heat to escape from the integrated circuit chips inside to an external heat sink. In this manner, and employing advanced cooling methods, a Micro Blade assembly can effectively handle the approximately 500 watts of power associated with a high-end 4-way server. The Micro Blade package typically occupies less than 1% of the volume of a conventional blade device that is fabricated using packaged devices mounted on printed circuit boards. This type of result provides motivation for the Micro Blade form factor.
An example blade server is the HS40 manufactured by International Business Machines; it is 2.3 inches thick, 9.7 inches high, and 17.6 inches wide. The HS40 can be inserted into a chassis having 16 slots for similarly shaped blade components. The components may have different functions such as processor modules, or switch modules for high data rate communications to or from other components.
The HS40 includes up to 4 Xeon processors. Because these processors each generate up to 85 watts of heat during operation, they are provided with large and bulky finned aluminum heat sinks; and forced air passes over the fins to cool the processors. These heat sinks occupy approximately 40% of the HS40 blade volume. The total blade electronics requires 480 watts of cooling when four 3 GHz processors are installed. The HS40 also includes a power supply board, a controller board, and memory provided within serial in-line packages; it weighs 15.4 pounds and occupies 393 cubic inches.